Table 5.

Pharmacology of fentanyl and buprenorphine transdermal patches[48-52]

	Fentanyl transdermal patch	Buprenorphine transdermal patch
Absorption	Bioavailability, 92%; Plasma protein binding, 79%-87%; Cmax, 2.6 μg/L; Effective time, 12.7-16.6 h; Peak time 38.1 h; AUC, 117 μg/L; H (0-72 h)	Bioavailability, 50%; Plasma protein binding, 96%; Cmax, 305 pg/mL; Onset time 21 h; Peak time, about 60 h; AUC, 20228 pg/mL
Metabolism	Metabolized by CYP3A4 in the liver, and the metabolites are basically inactive	Metabolized by CYP3A4 in the liver
Elimination	The half-life of the transdermal patch is about 17 h (13-22 h)	The half-life of the transdermal patch is 25.3 h
Mechanism	μ opioid receptor agonist	μ opioid receptor partial agonist, δ opioid receptor agonist, weak κ opioid receptor antagonist, ORL-1 agonist
Indication	Moderate to severe chronic pain and intractable pain treated with opioid analgesics	Chronic pain beyond the control of nonopioid analgesics
Dosage form specification	2.1-, 4.2-, 8.4- and 12.6-mg paste; Four specifications, lasting for 72 h	5-, 10- and 20-mg paste. Each paste is used for 7 d
Adverse reactions, > 10%	Nausea, headache, constipation, dry mouth, drowsiness, fuzzy consciousness, powerlessness, sweating	Erythema, pruritus, nausea

AUC: Area under the curve; ORL: Opioid receptor like; TDDS: Transdermal drug delivery system.